N-Acetylcysteine Slows Down Cardiac Pathological Remodeling by Inhibiting Cardiac Fibroblast Proliferation and Collagen Synthesis

Objective. By observing the effect of N-acetylcysteine (NAC) on the proliferation and collagen synthesis of rat cardiac fibroblasts (CFs) to explore the effect of NAC on cardiac remodeling (CR). Methods. In vivo, first, the Sprague Dawley (SD) rat myocardial hypertrophy model was constructed, and the effect of NAC on cardiac structure and function was detected by echocardiography, serological testing, and Masson staining. Western blotting (WB) and quantitative real-time polymerase chain reaction (qRT-PCR) were used to detect the expression level of antioxidant enzymes, and flow cytometry was used to detect the intracellular reactive oxygen species (ROS) content. In vitro, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay and 5-ethynyl-2 ′ -deoxyuridine (EdU) staining were used to detect cell proliferation, and the expression level of the NF-κB signaling pathway was detected. Results. Compared with the control group, the model group had disordered cardiac structure, reduced cardiac function, and obvious oxidative stress (OS) response. However, after NAC treatment, it could obviously improve the rat cardiac structure and cardiac function and alleviate redox imbalance and cardiology remodeling. At the same time, NAC can inhibit the activation of the NF-κB signaling pathway and reduce the proliferation level of CFs and the amount of 3H proline incorporated. Conclusions. NAC can inhibit AngII-induced CF proliferation and collagen synthesis through the NF-κB signaling pathway, alleviate the OS response of myocardial tissue, inhibit the fibrosis of myocardial tissue, and thus slow down the pathological remodeling of the heart.

Role of Oxidative Stress in Heart Failure: Insights from Gene Transfer Studies

Under physiological circumstances, there is an exquisite balance between reactive oxygen species (ROS) production and ROS degradation, resulting in low steady-state ROS levels. ROS participate in normal cellular function and in cellular homeostasis. Oxidative stress is the state of a transient or a persistent increase of steady-state ROS levels leading to disturbed signaling pathways and oxidative modification of cellular constituents. It is a key pathophysiological player in pathological hypertrophy, pathological remodeling, and the development and progression of heart failure. The heart is the metabolically most active organ and is characterized by the highest content of mitochondria of any tissue. Mitochondria are the main source of ROS in the myocardium. The causal role of oxidative stress in heart failure is highlighted by gene transfer studies of three primary antioxidant enzymes, thioredoxin, and heme oxygenase-1, and is further supported by gene therapy studies directed at correcting oxidative stress linked to metabolic risk factors. Moreover, gene transfer studies have demonstrated that redox-sensitive microRNAs constitute potential therapeutic targets for the treatment of heart failure. In conclusion, gene therapy studies have provided strong corroborative evidence for a key role of oxidative stress in pathological remodeling and in the development of heart failure.

Relationship between electrical myocardial instability and postinfarction remodeling in patients with ST-segment elevation myocardial infarction

Aim To study the clinical value of markers for myocardial electrical instability in combination with echocardiographic parameters for predicting the risk of cardiovascular complications (CVC) in the postinfarction period.Material and methods This study included 118 patients with ST segment elevation myocardial infarction (STEMI) and hemodynamically significant stenosis of one coronary artery. A percutaneous coronary intervention (PCI) with stenting of the infarct-related artery was performed for all patients. On day 7-9 and at 24 and 48 weeks after the treatment, ECG Holter monitoring was performed, which included analyses of ventricular late potentials, dispersion of QT interval duration, heart rate turbulence (HRT) and variability (HRV), and heart chronotropic load (HCL). At baseline and during postinfarction week 12, all patients underwent echocardiography with calculation of indexes of end-diastolic volume (iEDV) and end-systolic volume (iESV) to verify the signs of left ventricular (LV) myocardial remodeling. The criteria for LV pathological remodeling included increases in iEDV >20 % and/or iESV >15 % at 12 weeks after STEMI. The group without remodeling, R(-), consisted of 79 (67 %) patients and the group with signs of LV pathological remodeling, R(+), consisted of 39 (33 %) patients. Quality of life and achieved endpoints were evaluated during 144 weeks.Results By week 48 in group R(-), the stabilization of electrical processes in the myocardium was more pronounced as indicated by a decrease in HFLA by 12 % (р=0.004) and by a fourfold increase in RMS (р=0.047). Only in this group, the baroreflex sensitivity restored; pathological ТРС decreased from 20 to 5% (p=0.002) by the end of the active treatment. Stabilization of the repolarization phase duration in various parts of the myocardium was more active in patients without pathological remodeling as shown by decreases in disp QTa (р=0.009), disp QTe (р=0.03), sd QTa (р=0.006), and sd QTe (р=0.009). This was not observed in the group R(+). The recovery of vagosympathetic balance due to leveling the sympathetic component also was more effective in the group R(-), which was reflected in increased spectral and temporal HRV indexes (р<0.05). Both groups showed reduced HCL values at 24 weeks (р=0.047 and р=0.006); however, the HCL regression remained also at 48 weeks only in the group R(-) (р=0.006). Group R(-) patients reported higher quality of life (р=0.03) than group R(+) patients. Endpoints were achieved more frequently in the group R(+): 87.1 % vs. 27.8 % (odds ratio, 11.8; 95 % confidence interval, 4.6–30.8; р=0.00001).Conclusion Pathological myocardial remodeling in early postinfarction period is associated with electrophysiological instability of the myocardium, which results in the development of CVC and low quality of life in patients with STEMI.

The α2-isoform of the Na+/K+-ATPase protects against pathological remodeling and β-adrenergic desensitization after myocardial infarction

Reduced systolic and diastolic calcium levels in cardiomyocytes from NKA-α2 transgenic mice minimize the desensitization of the β-adrenergic signaling system. These effects result in an improved β-adrenergic reserve and prevent functional deterioration and cardiac remodeling.

The inflammation influence on pathological remodeling of pulmonary arteries in monocrotaline-induced pulmonary hypertension in rats

Aim To investigate the inflammation role on pathological remodeling of pulmonary arteries (PA) in monocrotaline-induced pulmonary hypertension (mPAH) in rats with joint assessment serum and tissue inflammatory biomarkers and the morphological arteries changes. Methods The mPAH was induced by a subcutaneous monocrotaline injection (60 mg/kg) in male rats and control group received a single saline solution. Baseline and every 2, 4, 6, 8 weeks after the serum concentrations of interleukin-6 (IL-6), interleukin-10 (IL-10) were measured by enzyme-linked immunosorbent assay; matrix metalloproteinase-9 (MMP-9), interleukin-1β (IL-1β), collagen type 1 and 3, smooth muscle actin α (SMA-α) in lung tissue were investigated immunohistochemically and quantitative measurements of intima and media thickness were done by planimetry. The functional activity neutrophil changes measured by chemiluminescence and fluorescent methods. Results The IL-10 increased after 2 weeks of mPAH (5,9 vs 0,6 pg/ml, p&lt;0,05) vs control and then it decreased to initial values by 8 weeks (0,06 vs 0,62 pg/ml, p&gt;0,05). The increasing IL-6 (30,3 vs 0,01 pg/ml, p&lt;0,05) and the maximum expression of IL-1β in the lung tissue (0,119 vs 0,099 index of expression (IE), p&lt;0,05) we observed 4 weeks after mPAH. The SMA-α (29,4 vs 40,2 IE, p&lt;0,05) and MMP-9 (1,6 vs 0,8 IE, p&lt;0,05) expression level significantly raised 4 weeks later vs control and remained in a high level until 8 week. A significant increase of type 1 collagen expression was observed at all phases of the experiment, and high level type 3 collagen expression was observed from 4 to 8 weeks (7,0 vs 10,4 IE, p&lt;0,05). The histological characteristics of remodeling these were a thickening of the media (30,6 vs 56,0 μm, p&lt;0,05) and the subintimal layer (1,6 vs 10,9 μm, p&lt;0,05) of the PA. 2 weeks after mPAH cell priming occurred which manifested by modification ROS generation systems, decrease NADPH oxidase activity, increase of myeloperoxidase secretion (MPO), enhance of unbound cytosolic calcium ions, mitochondrial potential reduction. From 4 to 8 weeks an increase NADPH oxidase activity and MPO secretion was revealed into the extracellular environment which leads to overproduction of hypochlorous acid. This functional activity reprogramming of circulating neutrophils indicate associated with time-development of mPAH. Conclusion The inflammation is the most important mediator of pathological remodeling processes in mPA. The monocrotaline launches a neutrophil reaction at an early stage of PAH with changes their functional activity which leads to immune cells recruitment into the lung tissue, producing inflammation and proliferation biomarkers. The hyperplasia of smooth muscle cells and reconstruction of the extracellular matrix are the result of this process and leads to increase intima and media thickness. The high MMP-9, SMA-α, IL-6 activity in 6–8 weeks reflects maintenance local inflammatory potential. FUNDunding Acknowledgement Type of funding sources: Public Institution(s). Main funding source(s): Basic and applied sciences - medicine, subprogram “Diagnostics and therapy of diseases” on the assignment “To establish the molecular-cellular mechanisms of the development of irreversible remodeling of pulmonary vessels in pulmonary arterial hypertension in an experiment in vivo.”

Lineage-specific regulatory changes in the pathological cardiac remodeling of hypertrophy cardiomyopathy unraveled by single-nucleus RNA-seq and spatial transcriptomics

BACKGROUND: Hypertrophy cardiomyopathy (HCM) is the most common cardiac genetic disorder with the histopathological features of cardiomyocyte hypertrophy and cardiac fibrosis. The pathological remodeling that occurs in the myocardium of HCM patients may ultimately progress to heart failure and death. A thorough understanding of the cell type-specific changes in the pathological cardiac remodeling of HCM is crucial for developing successful medical therapies to prevent or mitigate the progression of this disease. METHODS: We performed single-nucleus RNA-seq of the cardiac tissues from 10 HCM patients and 2 healthy donors, and conducted spatial transcriptomic assays of 4 cardiac tissue sections from 3 HCM patients. Comparative analyses were performed to explore the lineage-specific changes in expression profile, subpopulation composition and intercellular communication in the cardiac tissues of HCM patients. Based on the results of independent analyses including pseudotime ordering, differential expression analysis, and differential regulatory network analysis, we prioritized candidate therapeutic targets for mitigating the progression to heart failure or attenuating the cardiac fibrosis in HCM. Using the spatial transcriptomic data, we examined the spatial activity patterns of the key candidate genes, pathways and subpopulations. RESULTS: Unbiased clustering of 55,122 nuclei from HCM and healthy conditions revealed 9 cell lineages and 28 clusters. Significant expansion of vascular-related lineages and contraction of cardiomyocytes, fibroblasts and myeloid cells in HCM were observed. The transcriptomic dynamics during the transition towards the failing state of cardiomyocytes in HCM were uncovered. Candidate target genes for mitigating the progression to heart failure in HCM were obtained such as FGF12, IL31RA, BDNF, S100A1, CRYAB and PROS1. The transcriptomic dynamics underlying the fibroblast activation were also uncovered, and candidate targets for attenuating the cardiac fibrosis in HCM were obtained such as RUNX1, MEOX1, AEBP1, LEF1 and NRXN3. CONCLUSIONS: We provided a comprehensive analysis of the lineage-specific regulatory changes in HCM. Our analysis identified a vast array of candidate therapeutic target genes and pathways to prevent or attenuate the pathological remodeling of HCM. Our datasets constitute a valuable resource to examine the lineage-specific expression changes of HCM at single-nucleus and spatial resolution. We developed a web-based interface (http://snsthcm.fwgenetics.org/) for further exploration.